Multiple temperature refrigerating apparatus



Patented Feb. 9, 1943 APPARATUS MULTIPLE TEMPERATURE REFRIGERATING JohnJ. Shively, New York, N. Y.

Application November 2,1938, 'Serial No. 238,310

11 Claims.

This invention pertains to multiple temperature refrigerating apparatus.

In my Patent No. 1,907,885 are set forth and claimed a method andapparatus for the operation of a plurality of coolers in conjunctionwith an accumulator, by which the direct control and functioning of theindividual coolers are rendered substantially independent of theoperation of the primary refrigerating means.

An object of the present invention is to provide an improved apparatusfor controlling the refrigerating fluids within the accumulator andcoolers.

A further object is to provide improvedaccumulator and cooler apparatusfor carrying out the above method.

A still further object is to provide apparatus of the above typeparticularly adaptedto the maintenance of a plurality oftemperaturezones.

Another object is to provide apparatus of the above character comprisingmeans to maintain a plurality of independent temperatures in a singleunitary structure.

Still a further object is to provide means to operate a plurality ofcooling devices at different temperatures by means of a volatilerefrigerant thereinwhile maintaining substantially the same vaporpressure in all said devices.

will appear during the course of the following de-" scription inconnection with the accompanyingdrawing, in which s Figure 1 is-adiagrammatic vertical transverse sectional view of a three-temperaturestructure illustrating thecperation of the invention; Figure 2 is avertical sectional view of an native three-temperature structure;

Figure 3 is an exterior front view of the device shownnin r -11. I

Figure 4 is-a detail view ofthe type of liquid valve and lever shown inFigure 2:

Flgure5 is a fragmental detail view illustrating the use of internalvfins or the like toincreasethe interior condensing Fi ure 6 is adiagrammatic view or a formof altertwo-temperature unit embodying aflooded primary evaporator; and

' Figure 7 is a detail view of a means of distributing liquidrefrigerant in a secondary evaporator.

Referring to Figure 1, the numeral I0 generally denotes athree-temperature cooling unit having portions of coolers l2 and I3respectively into the upper portion of the accumulator or cooler II.Liquid passages I1 and I8 lead from the bottom of section II into theupper parts ofsections l2 and 13. The cooler sections I2 and I3 arepreferablyof inverted V-shape, and the passages l1 and I8 may terminatein short spouts l9 and 20 overlying the arched or sloped inner walls 2|and 22 forming the roofs of cooling compartments 23 and 24. The liquidpassages I1 and I8 are controllable by valves 25- and 26 adapted to beoper-' ated by any suitable thermostatic means, illustrated herein bythose of the well known type comprising elongated casings 21 and 28containing expansible bellows members (not shown) and havingthermostatic feeler" bulbs 29 and 30 connected thereto by tubes 3.! and32. The .bulbs may be disposed in any desired location with relation, totheir respective coolers. For instance, the bulb 29 is shown attached tothe outer surface of cooler l2, while bulb 30 is disposed within thecompartment 24.

One or more of the thermostatic bulbs may 'also be located in theatmosphere of a, refrigerator space to be cooled, as in the case of arefrigerator having two food storage spaces divided by. a par- .titionas, as illustrated by dotted and dashed lines, Figure 1.

- The accumulator I contains a body of volatile refrigerant 33, theliquid level thereof being below the openings of passages I5 and IS. Aprimary evaporator, illustrated by a coil 34, is disposed in theaccumulator II and has inlet and outlet pipes 35 and 36 leading throughthe walls thereof, the joints being permanently sealed to 31'. Liquidand suction lines 38 and 39 connect the expansion valve 31 andoutlet'pipe 36 with a condensing unit lllof any suitable type. Athermostatic switch 4|, adapted to control the motor surface in theaccumulator; Y

42 of unit 40, has the 'usualfeeler bulb 43 disposed inheat-exchange'relation with the accumulator manner,

section II, for in'stance in a sealed tube 44 as shown.

The accumulator section II and the liquid passages I! and I8 preferablyare provided with exterior insulation 45.

The operation of the device is as follows:

The condensing unit 40, operating in the usual circulates a primaryrefrigerant through the primary evaporator 34, thereby refrigerating thesecondary refrigerant bath 33. The thermostatic control 4| is soadjusted as to maintain the temperature in the accumulator section H atthe lowest temperature desired in the system; that is, a temperaturesubstantially below those at which the coolers l2 and I3 are intended tooperate.

The thermostatic valves 25 and 26 are set to open and close withintemperature ranges above that of the accumulator ll, since the coolersl2 and [3 are adapted to provide zones of higher temperature. Normally,therefore, while the valves 25 and 26 are closed, the interiors ofcoolers l2 and I3 are maintained substantially dry due to the fact thatany comparatively warm vapor from evaporation in these lower coolersrises through the open vapor passages l5 and I6,

gives up its heat to the low temperature bath 33, 'and is condensedtherein.

'When the temperature of bulb 29, controlling the valve 25 of cooler l2,rises to the maximum of its set range, the valve 25 opens and allowscold liquid from the bath 33 to fall through the passage I1 and spout l9into the interior of cooler l2.- This cold li'quid encounters andspreads over the inner surfaces of cooller l2, receives heat therefromand is vaporized at a temperature higher than that in accumulator II.The comparatively warm vapor thus evolved passes upward through thepassage l5 and is recondensed in the liquid bath 33. The evaporation incooler l2 refrigerates the latter until its the amounts of liquid fed or"spilled into them. Their individual temperature adjustments thereforeare entirely independent of each other, the only requirement being thatboth must operate at higher temperature than that of the accumulator orminimum. temperature section II. Similarly, except for theirhigherranges, the temperatures of coolers I2 and I3 have no fixed relationshipwith that of section H, since, if the temperature of the latter ischanged, the thermostatic valves 25 and 26 simply feed greater orsmaller amounts of the sub-coole liquid to their coolers as required. G

The interior surfaces of the coolers l2 and I3 may be shaped in anydesired manner to distribute the entering sub-cooled liquid in the mostadvantageous manner, those shown in Fig ure 1 having arched inner walls2| and 22 adapted to spread the film of liquid down both sides of thecooler.

Various distributing devices such as the spreader baflie 68 shown inFigure '7 may also be used.

Obviously the coolers may be provided with thick sections or with brinepockets for storage, with exterior or interior fins, etc., according tothe particular type of installation for which the device is to be used.

The valves 25 and 26 are required only to hold the smaller liquid headabove them, and need not close with absolute tightness, as small leakagewould have negligible effect on the operation, simply lengthening thetime between major openings of the valves. The valves therefore requirelittle power of their thermostats, which consequently for some purposesmay be of comparatively simple and cheap construction.

Figures 2 and 3 illustrate a three temperature unit in which the highertemperature coolers 46 and 41 are arranged vertically below the lowtemperature or accumulator section 48. The accumulator, section 48, isadapted to contain a body of liquid refrigerant 4811, with a vapor space38b above the liquid as in the case of Figure 1. The liquid valves 49and 50 at the lower ends of liquid passages Ila and Nb, respectively,

' are controlled by bimetallic helices SI and 52 freeizer compartment[4, and that the accumulated heat of the entire combinationis removedfrom the bath 33 by operation of the primary evaporator 34. As the bath33 is of substantlsll volume and therefore possesses considerable heatstorage capacity, it is also evident that the operation of the lowercoolers i2 and l3 takes place whether the condensing unit 40 is inoperation or not, the latterbeing controlled to maintain the bath 33always at lower temperatime than that of coolers l2 and i3. Since allcoolers are in free vapor communication with the upper portion ofaccumulator section II, all coolers are normally at substantially thesame pressure-the only difference existing at any time in their cyclesbeing the very small rise in vapor pressure in the lower coolers whichcauses their warmer vapor to move u through the passages I 5 and I6. vus, the coolers i2 and i3 are operated at 5 different temperatures notby any attempt to adapted to revolve rods 53 and 54 carrying smalllevers 55 and 56 engaging the valves as illustrated in Figure =4. Thebimetallic elements 5| and 52 are adjustably mounted at pointsrelatively remote from the inlets for the sub-cooled liquid so that thelatter does not directly influence their temperature, and the rods 53and 54 may be madeof Bakelite or of metal having low heat transmittingcoemcient such as stainless steel.

The thermostats arethus influenced principally by the heat transmissionand radiation of the adjacent cooler walls. Protecting and sealing caps51 mayv be provided over the adjustable mountings of the thermostats. Asshown, the accumulator or sharp-freezer section- 48 and the secondtemperature cooler 46 are insulated, from each other and from theoutside atmosphere by means of asuitable body of insulatin material 430,the second temperature cooler 44 is adapted to provide an intermediatetemperature compartment, while the bottom cooler 41, in addition toproviding a mild temperature storage compartment, is exposed to theatmosphere of the refrigerator to provide general cooling and may beprovided with exterior fins 58 for this purpose. Obviously thisarrangement of the middle and bottom coolers may bereversed.

and if desired both coolers 46 and 41 may be members, as shown forillustration in the construction of the primary cooling coil 59 and Isharp-freezer pocket 60, Figure 2.

To increase the interior cooling surface exposed to the vapors enteringthe accumulator, members such as fins 6|, Figure 5, may be employed. Themembers Bl, .which may either be attached to the primarycoil 62 or maysimply be loosely disposed within the accumulator 63, are partlysubmerged in the liquid bath 64. These members, through their largesurface above the liquid level, rapidly absorb heat from the vaporentering through the passage 65 and conduct it into the bath 64, bywhich means coninsulated or exposed, the latter arrangement is exposedto 'the atmosphere to refrigerate theevaporated from the correspondinglower cooler. The sharp-freezer or accumulator temperature continues tofall until further lowering is stopped by the thermostatic switch 4|,Figure 1, the lower cooler meanwhile being dried out or starved aspreviously described, and the system assumes its normal operationthroughout. During the above starting period from general warmconditions, if the compressor suction were to operate preferred in mostcases, as a certain amount of additional heat absorbed through them fromthe atmosphere serves to accelerate the upward passage of the vapors. Y

In the foregoing illustrations the primary evaporators have been shown.as employing expansion valves. Figure 6 shows diagrammatically a twotemperature unit :66 in which the primary evaporator uses the floodedsystem controlled by a float 61.

Instead of employing the binary system .asv hitherto described, thedevice may be constructed v for direct primary action by the high sideunit.

on the liquid bath in the accumulator. However, the binary system ispreferred for several reasons, of which the principal are as follows:

The binary arrangement permits the selection of primary fluid especiallyadapted to efllcient heat removal at low temperatures while a sec-'ondary fluid may be selected having other char-- acteristics mostsuitable for its particular service;

' coolers are substantially full of liquid, their total internal volumebeing preferably small enough that a substantial amount of liquid alsoremains in the accumulator. Under these conditions, when the compressoris started, the entire cooler systemat first is refrigerated at the sametime, since the liquid has free passage through all the thermostaticvalves. As the general temperature falls sufllciently to operate eachthermostat the latter closes its particular liquid valve, after whichthe continued lowering of the accumulator temperature causes theremaining liquid to be directly on the fluid .in the entire cooler unit,a heavy load would be imposed which would either require unduly largehigh side capacity or would require some type of automatic restrictingmeans to prevent overload. The limited absorbing surface of the primaryevaporator noted above, prevents this unduly rapid extraction of heatand thereby distributes the initial load over a longer period, allowingthe use of a comparatively small and inexpensive high side unit suitedto normal operation of the system.

In the preferred forms of the invention illustrated, the low sidestructure forms a complete, multiple temperature unit in which thesecondary fluid may be permanently sealed, the unit being adapted to beconnected to any suitable refrigerating machine in the same manner as anordinary single evaporator. The device has been illustrated as operatedin connection with a high side of the compression type, but it will beunderstood that it is also adapted to operate with absorption systems.

From the foregoing-description it will be seen that the inventionprovides a method of refrigerating a plurality 'of coolers whichconsists in 1'. Ina device of the character described, in-

combination, an accumulator casing adapted to contain'a substantial bodyof volatile liquid,

means including a primary evaporator in said casing in heat exchangerelationship with said liquid and adapted to refrigerate said'liquidwithin a pre-determined temperature range, a freezing compartment insaid casing, a plurality of secondary evaporators disposed at lowerlevel than said casing, a body of insulating material between saidcasing and said secondary evaporators, means forming individual passagesentirely within said body of insulation and adapted to admit quantitiesof said liquid from said body to said secondary evaporators, individualthermostatic means .operable in-accordance with ,the individualtemperatures of said secondary evaporators to control said admissions,the upper limit of said pre-determined temperature range being below anyof said individual temperatures, and

individual vapor conduits exterior to said insulation and in opencommunication from said secondary evaporators to said casing. i

2. The combination claimed in claim 1 including means to adjust saidrefrigerating means to vary said pre-determined range and wherein saidrefrigerating means.

the lower part of said easing into said evaporator; a valve adapted tocontrol the flow of said liquid through liquid conduit, thermostaticmeans to control said valve in accordance with the temperature of saidevaporator, and refrigerating means to maintain said body of fluid insaid accumulator at a temperature lower than the temperature of saidevaporator, said accumulator casing including means to conduct heat froman exterior substance directly to said body and said refrigeratingmeans. 4

4. The combination claimed in claim 3 wherein said volatile fluid isconfined entirely within said casing, evaporator and conduits, andwherein said refrigerating means. includes a primary evaporator in heatexchange relationship with said fluid in said casing; said primaryevaporator havinga plurality of heat absorbing fins extending above thelevel of said body of fluid in said accumulator.

5. The combination claimed in claim 3 wherein said refrigerating meansincludes means to adjust the temperature maintained in said accumulator,wherein said valve is disposed at the delivery end of said conduitwithin said evaporator, and wherein said thermostatic valve controlmeans is adjustable independently of said accumulator temperature. 6,The combination claimed in claim 3 wherein said thermostatic means iscomprised in said evaporator in heat exchange relation with a wallthereof.

7. In a device of the character described, in combination, anaccumulator comprising, a chamber adaptedto contain a substantial bodyof volatile refrigerant, means forming an insulating body engagingsubstantially the entire lower exterior surface of said accumulator, anevaporator comprising a second chamber below said first chamber andhaving an upper exteriorwall engaging said insulating body, an interiorwall of saidsecond chamber comprising an upwardly arched middle portionand substantially vertical side portions. an open vapor conduit outsidesaid insulating body and connecting the upper portions of said first andsecond chambers, a

liquid refrigerant conduit leading through said insulating body from thebottom of said first chamber into the top of said second chamberdirectly above said arched wall portion, a valve adapted to control theflow of liquid through said conduit, thermostatic means to control saidvalve, means to refrigerate said body of refrigerant in saidaccumulator, and means forming a freezing chamber within saidaccumulator.

8. A unitary cooling device comprising in combination, an upper tankadapted to hold a substantial body of liquid refrigerant and having avapor space above said liquid, a second tank directly below said firsttank and comprising a single chamber of inverted U-shape, an insulatingbody between said tanks and engaging the same, a vapor conduit outsidesaid insulating body and leading from the upper portion of said chamberto said vapor space in said first tank, a liquid conduit from thebottomof said first tank into the top of said inverted U-shaped chamber, avalve adapted to control liquid flow through said conduit, thermostaticmeans to control said valve, and an evaporator in said first tank,

9. A unitary cooling device comprising in combination, anupper cooleradapted to hold a substantial body of volatile liquid refrigerant andhaving a vapor space above said body, a lower cooler under said uppercooler, an open vapor conduit connecting the upper portion of said lowercooler with said vapor space, a liquid conduit connecting the lowerportion of said first cooler with'the top of said second cooler, arefrigerating evaporator in said first cooler, and a plurality of heatconducting member of substantial surface disposed in said first coolerand extending from below the surface of said liquid body into said vaporspace. j

10. In a unitarycooling structure, in combination, an accumulator.adapted to contain a substantial body of liquid refrigerant, saidaccumutor into the upper portions of sai 'evaporators, valves in saidevaporators at the ends of said liquid conduits, thermostatic meanscomprised entirely within said evaporators and adapted to control saidvalves, and means to refrigerate said liquid in said accumulator. 1l.Astructure as claimed in claim 10 wherein said first and secondevaporators are of-inverted U-shape and including heat-absorbing fins onsaid second evaporator.

- JOHN J. SHIVELY.

